Field of the Invention
The present invention relates to methods for manufacturing a ceramic formed body, and apparatuses for manufacturing a ceramic formed body.
Description of the Related Art
Conventionally a ceramic formed body, which is configured as a honeycomb structure having a honeycomb shape, for example, has been used for a wide range of purposes, including a catalyst carrier to purify exhaust gas from automobile, a filter to remove diesel particulates, or a heat storage member for combustion devices. A ceramic formed body is manufactured by extrusion of a forming raw material, followed by a firing step to fire it at a high temperature. A honeycomb structure as one form of the ceramic formed body has a lattice-shaped partition wall that defines a plurality of polygonal cells extending from one end face to the other end face and forming a through channel of fluid.
A forming step to extrude a ceramic formed body into a desired shape is performed using an extrusion machine having an extrusion port to which an extrusion die of a desired shape is attached, so as to extrude a forming raw material from the extrusion die with a predetermined extrusion pressure and at extrusion speed while keeping a horizontal extrusion direction.
For the forming raw material, various types of ceramic raw materials and binders, for example, are used, which are mainly in a powder form or a fine particle form. Then in order to allow such a material to be extruded from the extrusion machine, liquid such as water and/or surfactant is added at the mixing step to mix the ceramic raw materials or the like. This mixing step is typically performed using a batch-type mixer (batch mixer) firstly to dry-mix two types or more of aggregate particle raw materials including the ceramic raw materials as stated above that are weighed based on the predetermined mixture ratio (first mixing), to which liquid (water) is added for wet mixing (second mixing), whereby wet mixture (formulation for forming) is obtained (see Patent Document 1). Thereafter, the wet mixture (formulation for forming) prepared by wet mixing is kneaded at a kneading step, and then a forming raw material having predetermined viscosity that is adjusted suitably for extrusion is extruded from an extrusion machine.
[Patent Document 1] WO2005/018893